import java.net.MalformedURLException;
import java.net.URL;
import java.security.CodeSource;
import java.security.cert.Certificate;

public class Main {
    public static void main(String[] args) throws MalformedURLException {
        URL url = new URL("http://localhost/file");
        CodeSource csEmpty = new CodeSource(url, new Certificate[0]);
        CodeSource csNull = new CodeSource(url, (Certificate[]) null);
        if (!csEmpty.implies(csNull)) {
            throw new SecurityException("Empty certificates should imply null certificates");
        }
    }
}